At present in commercial cooking equipment foods are boiled, fried or heated in containers which are shaped to include a bath or tank in which the foodstuffs are placed while cooking.
The baths are heated in a number of ways, for example with an electric element or elements and by burning gas which heats the lower region of the bath in which the cooking liquid is retained.
A problem with existing fish fryers is that if the surface area heating the oil or fat is directly heated, for example, by a blue flame burner heating a steel panel on the other side of which is contained the oil, etc., that surface area can overheat. Any overheating can cause fatty acids to develop quickly with a result that oil life is substantially reduced. Moreover, the life of the steel panel, or heat exchanger, is also substantially reduced.